Continuous plating apparatus

ABSTRACT

An apparatus for continuously plating a sheet of a metal such as steel comprising means for feeding a sheet to be plated, pretreatment baths, a plating bath, aftertreatment baths and a winder for taking up the plated sheet all arranged successively in a row, said baths having therein aligned slits for allowing the sheet to be passed linearly therethrough in a manner that the sheet is held vertical, said plating bath having therein means for causing plating liquid to flow in parallel relation with the sheet whereby a plating of good quality may be rapidly attained without any fold and wrinkle produced in the sheet.

United [72] Inventors States Patent Kaname Nakao Neyagawa-shi;

Takashi Suzuki, Takatsuki-shi, both of Japan 21 Appl. No. 829,265

[22] Filed [45 Patented [73] Assignee [32] Priority June 2, 1969 Oct. 26, 1971 Matsushita Electric Industrial Co., Ltd.

Osaka, Japan June 4, 1968 Japan 43/38927 [54] CONTINUOUS PLATING APPARATUS 3 Claims, 15 Drawing Figs.

6/l930 Harrison 8/ 1 931 References Cited UNITED STATES PATENTS Smith Primary Examiner-John H. Mack Assistant Examiner-William 1. Solomon Attorney-Stevens, Davis, Miller & Mosher ABSTRACT: An apparatus for continuously plating a sheet of a metal such as steel comprising means for feeding a sheet to be plated, pretreatment baths, a plating bath, aftertreatment baths and a winder for taking up the plated sheet all arranged successively in a row, said baths having therein aligned slits for allowing the sheet to be passed linearly therethrough in a manner that the sheet is held vertical, said plating bath having therein means for causing plating liquid to flow in parallel relation with the sheet whereby a plating of good quality may be rapidly'attained without any fold and wrinkle produced in the sheet.

PATENTEUnm 26 I971 3,616,426

SHEET 1 0F 6 9 him m/ 2 INVENTORS Wanker/6 ATTGR NIZYS PAIENTEnnm 26 m1 3,616, 12 6 SHEET 3 [1F 6 FIG. 5

1 1/1 1 I 11 1 11 I IIIII/ PATENTEUum 2s 19?! 3,616,426

SHEET u [If e 1 CONTINUOUS PLATING APPARATUS This invention relates to an apparatus for continuously plating sheet or ribbon of a metal such as steel. The apparatus utilizes a small-sized plating bath while making it possible to rapidly obtain a plated layer of uniform thickness and good quality.

It has heretofore been usual to apply plated layer onto previously shaped or formed articles or machine parts. However, difficulties have been recognized in that feeding in of ,such previously shaped articles and conveying out of plated articles have required complicated and less efficient operations. Thus, it is commonly put into practice to work or shape, such as by pressing, previously plated sheet of metal into articles of required configuration.

As shown in FIG. 13, however, prior art continuous plating of a ribbon of a metal usually utilizes sink rolls d so as to keep the ribbon c dipped in the plating bath b contained in a plating tank a. The sink rolls bend or turn the ribbon substantially at 180. This causes folds and wrinkles to be produced in the ribbon. In addition, thickness of the ribbon to be plated is inevitably limited by the use of the sink rolls.

Substantial dimension is required between electroconductive rolls e and effective surface to be plated, which requires increased amount of electric power. Furthermore, the ribbon of metal is advanced zigzag, with the result that a number of rolls and increased amount of electric power are required.

The conventional plating method is carried out by use of static bath which is agitated by air. Thus, conventional plating is to be carried out under lower current density. For example, prior art nickel plating may have its maximum current density of up to A. /dm. This adversely affects the efficiency in plating operation in that the speed of plating operation is influenced by the speed at which the metallic ions diffuse in the plating bath. In order to speed up the winding of the plated ribbon, therefore, there was no measure but elongating the length of the plating bath.

In addition, the ribbon c is not disposed in parallel and faced relationship to a positive electrode f, with the result that greater amount of deviation is seen in the thickness of plated layers. For example, there is produced a deviation in the order of :2 3p. from the predetermined thickness of 5 [1,, which means deviation of about 50 percent. Thus, it is apparent that with the conventional plating method, it is impossible to efficiently obtain a plated layer of high quality.

The present invention contemplates eliminating the abovestated prior art disadvantages and difficulties as well as providing a small-sized and efficient plating apparatus.

An object of the present invention is to prevent any fold and wrinkle being produced in the ribbon and obtain a plated layer of good quality by the use of an arrangement that means for feeding ribbon to be plated, pretreatment baths for cleaning the surfaces of the ribbon, at plating bath for plating the ribbon and a winder for taking up the ribbon are all disposed in a linear row, said pretreatment and plating baths being provided with slits through which the ribbon is linearly passed with the web of the ribbon being kept upright or vertical, said plating bath being further provided with a pair of anode plates disposed in parallel and facing relationship to the ribbon whereby the ribbon is advanced along a linear path of travel throughout the entire sections for the steps of pretreating, plating, and after treating.

Another object of the present invention is to provide a continuous plating apparatus having means for feeding plating liquid into the space between the anode plates along paths of flow parallel thereto so that the plating liquid is maintained at high concentration whereby plating is proceeded at increased rate with high electrical density.

A further object of the present invention is to simplify the mechanism for advancing the ribbon as well as to decrease the necessary power by the utilization of an arrangement that means for driving a winder for the ribbon are designed to drive current collector rolls for the negative charge of the ribbon, which rolls are caused to also serve to advance the ribbon.

The present invention also relates to improvements in a steam grease-removal tank and electrolytic grease-removal cell to be used in pretreatment step and improvements in water-washing and pickling tanks. Furthermore, the invention also relates to improvements in the compositions of plating liquids for nickel plating and tin plating, respectively.

Other objects and features of the present invention will be made apparent from the following description in conjunction with the accompanying drawings.

FIG. 1 diagrammatically illustrates an embodiment of the continuous plating apparatus according to the present invention;

FIG. 2 is a perspective view of a section for feeding a continuous sheet of a metal to be plated;

FIG. 3 is a vertical sectional view of a steam grease-removal bath;

FIG. 4 is a perspective view of cooling coils for use with the steam grease-removal bath;

FIG. 5 is a plan view of an electrolytic grease-removal bath;

FIG. 6 is a vertical sectional view of the electrolytic greaseremoval bath shown in FIG. 5;

FIG. 7 is a perspective view of a water-washing bath;

FIG. 8 is a schematic vertical sectional view of a plating bath;

FIG. 9 is a perspective view of the main body of the plating bath;

FIG. 10 is a plan view of the main body shown in FIG. 9;

FIG. 11 illustrates in perspective view a sheet metal take-up section and drive section therefor;

FIG. 12 is a perspective view ofcurrent collector rolls;

FIG. 13 illustrates in vertical section a prior art plating bath;

FIG. I4 is a graphical illustration of variation in the thickness of plated layer obtained by use of the apparatus according to the present invention; and

FIG. 15 is a graphical representation of consumption of respective components contained in the plating bath.

Referring to the drawings and, particularly, to FIG. I, numeral 1 denotes an object to be plated, that is, a continuous sheet of steel. The plating apparatus of the present invention comprises a steam grease-removal bath 2, an electrolytic grease-removal bath 3, a water-washing bath 4, a pickling bath 5, a water-washing bath 6, a plating bath 7, a water-washing bath 8, a drying room 9 and a winder I0 all arranged in a linear row. These baths and room are provided with aligned slits through which the metal sheet or ribbon is allowed to pass. The plating apparatus in this embodiment has its full length of approximately 8,000 mm.

A further detailed description will be made hereunder with respect to respective sections of the apparatus: The ribbon of the steel 1 is wound in the form of a coil which is mounted vertically on a mount 11 as shown in FIG. 2. The steam grease removal bath 2 is provided therein with partitions l2, 12 between which is contained a solvent 13 (FIG. 3). The latter is heated by a heater 14 which produces vapor 13' for removing the grease on the ribbon of the steel when passing through the atmosphere of the vapor 13'. A coil of cooling tube 15 is provided between the partitions I2, 12 above the heater I4. Outside of the partitions 12, 12 are provided cooling boxes I7, I7 each housing coils of cooling tubes l6, 16 (FIG. 4) on the opposite sides of the steel ribbon I passing through ribbonpassing slits 18, I8 in the partitions I2, I2. The vapor escaped through the slits l8, 18 is liquidized within each box 17 and is discharged through a drainage pipe 19.

As seen in FIGS. 5 and 6, the electrolytic grease-removal bath 3 has therein a central partition 20 containing a greaseremoving liquid 2] and solution feeding and discharging pipes 22, 23 at the upper and lower sections of the bath, respectively. A pump (not shown) is operated to positively circulate the grease-removing liquid through the pipes 22 and 23 and maintain the level of the liquid within the bath 3 suflicient for the steel ribbon I to be dipped thereby.

Packings 24, 24 of elastic material are mounted in the ribhon-passing slits 25, 25 in the partition 20 to prevent leakage of the liquid therethrough. in order to completely prevent a leakage of the liquid 21 outwardly of the grease-removal bath 3, provided outwardly of the partition are a plurality of partitions 26, 26 whose slits 27, 27' are also provided with similar packings 28, 28'. Anode plates 29, 29 are disposed within theelectrolytic grease-removal bath 3.

As shown in FIG. 7, the water-washing bath 4 is so designed as to feed water into the inside of a partition 30 having slits 31. The bath 4 also has an outer partition 32 having slits 33. The slits 31 and 33 in the inner and outer partitions 30 and 32 are also fitted with packings similar to those mounted in the electrolytic grease-removal bath 3. A brush 34 of nylon is provided to raise the efficiency in water-washing the ribbon l. The water-washing baths 6 and 8 are of the structures similar to that of the aforestated water-washing bath 4.

By referring to FIGS. 8-10, a description will next be made with respect to the plating bath 7. The bath 7 includes a main body 35 of a chemicals-resistive plastic material having therein a liquid feeding nozzle 36 of less than 30 so as to produce parallel flows of the liquid and of such design as to speedup the liquid flow within the body 35. Pipes 37 each having therein a pump P are provided to supply a plating liquid from a tank 38 to the main body 35. Another tank 39 is disposed'to receive plating liquid discharged from the main body 35 through a drainage pipe 40 provided in the rearward section of bottom thereof. Within the tank 39, the plating liquid is conditioned with respect to its temperature, pH and concentration of metallic ions and then is pumped through a pipe 41 having therein a pump P to the tank 38. Provided adjacent the opposite sidewalls of the main body 35 are positive electrodes 42 which are in positive charge. Perforated obstruction plates 43, 43 of electrically insulating material such as polyvinyl chloride are each disposed between each positive electrode 42 and the ribbon l to prevent a short circuit which would otherwise be produced between the ribbon 1 and any one of the positive electrodes 42, 42. The obstruction plates 43, 43 also function to enable the ribbon 1 to be linearly advanced and facilitate parallel flows of liquid in the bath.

The plating tank 35 is provided with an inlet slit 44 to which is fitted a packing 45 of electrically insulating material such as polyvinyl chloride or rubber. The packing 45 may be exchanged by another similar packing so as to adapt change in thickness or width of the ribbon. A partition 46 is provided within the main body 35 at the location rearwardly of the point of connection of the pipe 40 to the body 35. The partition 46 has a slit 47 which is provided with a packing 48 of an elastic material such as rubber, the packing 48 serving to prevent leakage of the liquid contained in the tank 35.

The drying room 9 is of the type that utilizes heated air.

FIG. 11 illustrates the winder 10 for the ribbon l and a driving mechanism therefor. The drive mechanism includes a stepless speed change ring cone 49 which is in driving connection through a chain 50 to a shaft 51 which in turn is connected to rotary rolls and is drivingly connected through a chain 52 to a winder shaft 53. A brake 54 is provided for the control of the winder shaft 53. The rotational speed of the rotary rolls and the winder shaft is controlled by manually adjusting a controller 55 provided on the ring cone 49.

As fragmentarily shown in FIG. 12, a plurality of current collector rolls 56 of copper, which rolls are for applying negative charge to the ribbon l, are each driven by a gear 59 which in turn is driven through a chain 58 by a gear 57 fixed on the shaft Sl. Each pair of rolls 56 is in sliding contact with a current conduction brush 60 so as to be electrified with negative electricity by the brush. Thus, the rolls 56 are driven by the ring cone 49 so as to serve as feeding or advancing rolls for the ribbon l in addition to serving as current conductors to the ribbon. Numeral 61 represents a lead wire.

.Mark l" in PK]. 1 represents a pump for circulating liquid for the electrolytic grease removal. Mark P denotes a pump for circulating liquid for pickling. Numerals 62 indicate auxiliary rolls operatively connected to the shaft 5 l.

As exemplified in the above, the plating apparatus according to the present invention comprises a steam grease-removal tank, an electrolytic grease-removal tank, a water-washing tank, pickling tank, a water-washing tank etc. for the pretreatment, a plating tank, and a water-washing tank, a drying room, etc. for the aftertreatment, all arranged successively in a linear row. in addition, the treatment tanks and the plating tank and the drying room are provided with slits through which the ribbon to be plated is passed along a linear pass of travel. Furthermore, the plating tank is provided with a pair of anode plates disposed in parallel and facing relationship to the run of the ribbon. Thus, there is no possibility that the ribbon suffers from folds and wrinkles produced therein and it is possible to plate a ribbon of relatively larger thickness.

Moreover, plating liquid in the plating tank is positively caused to flow or move in parallel with the run of the ribbon by the circulation of the liquid, with the result that uniform and smooth diffusions and movements of the metallic ions in the bath are attained on opposite sides of the ribbon. This makes it possible to perform plating operation at higher current density. It also becomes possible to use bath of higher concentration. In addition, bath control is made easy, which leads to an achievement of high quality of plating. Furthermore, the plated layer is uniform throughout all of the areas or zones in the surfaces of the ribbon in that the anode plates are disposed in parallel and facing relation with the run of the ribbon within the plating bath. Furthermore, the winder for the ribbon and the drive therefore are disposed rearwardly of the drying room and the current collector rolls for electrifying the ribbon with negative electricity are operatively connected to the drive. This not only enables the collector rollers-to also serve as advancing rolls, but also simplifies the mechanism for advancing the ribbon, with resultant minimization of the necessary power force. incidentally, the ribbon passage slits in the respective treatment tanks and the drying room are all opened upwardly so that the ribbon may conveniently be set or placed therein.

Still further, it is another advantage of the present invention that a plating tank of smaller size can be used because of the fact that the plating bath is positively caused to flow. For instance, a plating tank of 200 liter capacity, one third of a conventional tank in capacity, can have its capability equal to that of the conventional tank. Since, however, the volume of the bath is considerably reduced as compared with the amount of the products, the composition of the plating liquid is subjected to remarkable variation. Thus, in order to make better use of the aforestated advantageous features, the plating liquid should be of improved and unique composition.

While the present invention may widely be applicable to platings of copper, zinc, lead etc, description will hereunder be made with reference to the results of studies in connection with the liquids for nickel and tin platings.

As to nickel plating, preferable liquid composition and electrolytic condition are as follows:

LIQUID COMPOSITION nickel sulfate nicltel chloride 60-80 g./l. boric acid ELECTROLYTlC CONDlTlON lO-Zl) mm. -180 mJruin.

Lil-L5 mJmin.

In case of a plating liquid including less than 450 g./l. of nickel sulfate, less than 60 g./l. of nickel chloride and less than 45 g./l. of boric acid, the absolute contents in the liquid is so small that variations will remarkably occur in the liquid and pH. So as to maintain the quality, therefore, it is always required to supply components of the liquid. If, however, plating operation is proceeded immediately after the supply of the liquid components, the resultant film of the plated layer will be fonned therein with pits and rendered poor in quality. Thus, after the supply of liquid components, it is required to wait for a while until the components become well ripe. It may, therefore, be said that in case of a thin or weak liquid, conditioning of the bath requires considerable amount of labor. In case of a plating liquid including more than 600 g./l. of nickel sulfate, more than 80 g./l. of nickel chlorfie and more than 60 g./l. of boric acid, the plating liquid is thicker in concentration and has an increased specific gravity. In this case, therefore, the liquid bath will have a decreased speed of flow and, in order to raise the speed of flow, the pump of larger power will be required. In addition, when the liquid is of a concentration to such extent, the liquid components will hardly be melted. Thus, it is required to heat the bath to 80 C. This is disadvantageous and uneconomical in that, in order to achieve that purpose, the plating tank must be made of expensive materials.

FIG. 14 graphically illustrates deviation in the thickness of plated layers obtained according to the above-described embodiment and under the condition that the speed of the ribbon was I m./min. and the speed of bath flow was I20 m./min. for the plating tank length of 1,500 mm.

FIG. also graphically illustrates variations in the bath components relative to amount of current supply and also illustrate amount of consumption of nickel anode plate.

As will be clear from the illustration of FIG. 15, the supplies of respective bath components for 1 AHr. of current supply were I g. of nickel component, 500 mg. of nickel sulfate component and 30 mg. of boric acid. Stable pH was attained in this way and a plating of fixed quality was obtained.

Another advantage of this nickel plating method is that soft and flexible plated layer can be obtained owing to lower pH of the plating liquid which is another characteristic feature of the invention. For example, the above-described plating method was applied to a blank of SPMA, Vickers hardness of 80-90 (Hc 25 g.), yield point of 23.] kg./mm. tensile strength of 31.8 kg./mm. and elongation of 52.8 percent. This resulted in a plated layer of 5 u in thickness, Vickers hardness of I-I50 (Hc g.), yield point of 22.8 kg./mm. tensile strength of 32.1 kg./mm. and elongation of 42.4 percent. The plated layer was soft and flexible and the plated blank represented a better press-workability.

Next, preferable liquid composition and electrolytic condition for tin plating are shown hereunder:

In order that the liquid may withstand being subject to continuous positive circulation, the liquid is added with 0.5-1.0 g./l. of erythorbic acid or a salt thereof, for example, sodium salt of erythorbic acid as an agent for preventing oxidization 6 and precipitation.

ELECTROLYTIC CONDITION Bath temperature 20-30 C. Current density lS-JO AJdm.

In case of a plating liquid including less than I00 g./l. of stannous sulfate, the liquid contains so small absolute amount of stannous ions that the liquid is subject to wider and remarkable liquid variation, which affects adversely the quality of plating. However, a quantity of more than I50 g./l. of stannous sulfate will hardly be melted at a bath temperature of lower than 30 C. and will form a pastelike deposition.

Plating was applied to a ribbon of steel according to the above-described plating method and with the condition that the length of the plating bath was L500 mm., speed of ribbon advancement was 1.5 m./min. and speed of bath flow was I20 m./min. The deviation in thickness of the resultant plated layer of tin showed a tendency similar to that of nickel plating which is seen in FIG. 14. This means that the layer of plated tin is of better quality.

What is claimed is:

l. A continuous plating apparatus comprising means for feeding ribbon to be plated, pretreating bath containers arranged in series for cleaning the surfaces of said ribbon, said pretreating bath containers comprising a steam greascremoval container, an electrolytic grease-removal container, a water-washing container, a pickling container and a second water-washing container; a bath container for plating said ribbon; a bath container for cleaning the plated ribbon; means for drying the cleaned ribbon; winding means for taking up said ribbon; all of said bath containers and means being ar ranged in a linear row, said pretreating bath containers, plating bath container, cleaning bath container and drying means being provided with slits for allowing said ribbon to be passed linearly therethrough with the web of said ribbon being maintained vertical, each of said slits being provided with a packing for preventing leakage, said plating bath container being provided with a pair of anode plates disposed in parallel and facing relationship to the run of said ribbon, rolls for holding said ribbon and electrifying the same; said plating bath container being provided with a nozzle for directing the flow of plating liquid in parallel relationship to the run of said ribbon within said plating bath container, a first tank in communication with said nozzle for containing said plating liquid and a second tank in communication with said plating bath container for receiving the liquid discharging from said plating tank, and means for pumping such plating liquid into said nozzle, said second tank being in communication with said first tank, said rolls all being'disposed outside of all of said bath containers; a single power source; a power transmission mechanism for transmitting driving force from said power source and driving said winding means and said electrifying rolls.

2. A continuous plating apparatus as claimed in claim I in which said plating bath container is provided therein with perforated obstruction plates of electrically insulating material disposed between said anode plates and the run of said ribbon.

3. A continuous plating apparatus as claimed in claim 1 in which said steam grease-removal bath container is provided therein with means for heating the grease-removing liquid and cooling boxes disposed outside of partitions of said greaseremoval bath, said cooling boxes including cooling coils for cooling and liquidizing the vapor of said grease-removing liquid.

t 0 i t I UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION 3,616,426 Patent No. Kaname NAKAO Dated October 1971 Inventor(s) Kaname NAKAO et al It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below: In the Priority Claim, only one of seven prior Japanese patent applications is listed, therefore, it is requested that the remaining six applications be listed as follows:

-Japan, Patent Appln. N 36859/69 filed May 8, 1969; Japan, Patent Appln. N 36861/69 filed May 8, 1969,- Japan, Patent Appln. N 36862/69 filed May 8, 1969; Japan, Patent Appln. N 36863/69 filed May 8, 1969; Japan, Utility Model Appln. N 47368/68 filed June 4, 1968; Japan, Utility Model Appln. N 43836/69 filed May 8, 1969.

Signed and sealed this 2nd day of May 1972.

(SEAL) Attest:

EDWARD M.FLETCHER, JR. ROBERT GOITSGHALK Attesting Officer Commissioner of Patents RM PO-1050 [10-69) USCOMM-DC 60376-P69 9 U 5 GOVERNMENT FIHNT NG OFFICE H6! O-355334 

2. A continuous plating apparatus as claimed in claim 1 in which said plating bath container is provided therein with perforated obstruction plates of electrically insulating material disposed between said anode plates and the run of said ribbon.
 3. A continuous plating apparatus as claimed in claim 1 in which said steam grease-removal bath container is provided therein with means for heating the grease-removing liquid and cooling boxes disposed outside of partitions of said grease-removal bath, said cooling boxes including cooling coils for cooling and liquidizing the vapor of said grease-removing liquid. 